Electric switch



Mm'uh "17-, 1942. J. L. CREVELING ELECTRIC SWITCH Filed Feb. 6, 1939 INVENTOR! .n/ n W W 1 Mn 6 2- W w a O L M a r Patented Mar. 17, 1942 UNITED STATES PATENT OFFICE ELECTRIC SWITCH John L. Creveling, near Tucson, Ariz. Application February 6, 1939, Serial No. 254,859

18 Claims.

My invention pertains to electric switches of the type used to open and close an electric circuit automatically, under desired conditions, and is particularly useful in systems where a source of voltage subject to variation in value is used to supply a circuit containing a counter electromotive-force, as a storage battery, for example, and will therefore be described with respect to such a system.

An object of my invention is to provide a switch which will connect the source of voltage with the circuit to be supplied thereby and having a counter E. M. F., when both voltages are very nearly or substantially equal throughout wide changes in the counter E. M. F.

Another object of my invention is to provide such a switch which will open the circuit when the voltage of the source of supply tends to fall below that of the circuit to be supplied, and thus prevent back discharge through the supply circuit.

Another object of my invention is to provide such a switch which will be reliable, compact, and capable of carrying relatively large current.

Another object is to provide such a switch which will be rugged, capable of standing vibration without unfavorably affecting its operation, and which will not be subject to accidental closing at such times as it is desired the switch should remain open.

Another object of my invention is to provide such a switch which may be manufactured cheaply, and in which the contact or contacts may be held under heavy pressure which will increase as the current to be carried increases.

Other objects will be plain from the following description and claims:

In the drawing,

Fig. I is a front elevation of one type of switch comprehending my invention, which I have found very useful in service.

Fig. II is a side elevation of the structure of Fig. I.

Fig. III is a top plan and partial section of the structure of Figs. I and II, the section being taken on the lines A-B of Fig. I, and CD of Fig. II.

Fig. IV is a diagrammatic representation of the structure of Figs. I, II and III, in use in a system having a storage battery supplied by a generator.

Fig. V is a similar diagrammatic representation of a modification that may be made in the structures of Figs. I, II and III.

Fig. VI is also a diagrammatic representation of a modification which may be made in the system of Figs. I, II and III.

In all the above noted figures, several coils or windings are shown; but, in Figs. I, II and III, the connections of the coils are omitted for sake plained; and when of clearness in illustration, and their connections are clearly indicated in Figs. IV and V.

Referring particularly to Figs. I, II, III and IV, I indicates a backboard or base, of insulating material, supporting the elements of my improved switch.

Upon the sides of the base I are fastened L- shaped, heavy, conducting members 2 and 3, which have their upper ends 4 and 5 formed to be readily connected into the circuit to be controlled by the switch and their other ends so arranged as to form the contact members 6 and 1. Between the members 2 and 3 is mounted the M-shaped magnet frame, comprising yoke 8 and limbs 9, l0 and II, supported by the nonmagnetic members l2 and provided with the coil or winding [3 upon its central leg in.

Below the electro-magnet 8, 9, ID, II and I2, the armature I4, provided with the bridging member I5, is supported by the member of mag netic material l6, in such manner as to be free to revolve within certain limits about the pivot H in a horizontal plane, and to be movable toward the magnet 8, 9, I 0, H, I2 against the action of spring l8, surrounding the pivot pin I! which passes with a slip fit through the member l6, as shown. The member I6 is provided with a coil or winding I9, and has one end 20 connected with the central portion of the yoke 2| of the magnet core 2|, 22, 23, as shown in Figs. II and VI. The limbs 22 and 23 are pro- Vided with the coils or windings 24 and 25, respectively. The screws 26 and 21, which are made of non-magnetic material, adjustably limit the movement of the armature M in a horizontal plane by striking the faces of the magnet cores 22 and 23. 28 is a flexible contact member carried by the strap 29 surrounding the member 2-6, and insulated therefrom as indicated at 30. When the armature I4 is revolved 'so that the screw 2'! approaches the magnet core 23, the right hand extremity of the bridging member l5 makes contact with the flexible member 28, as shown in Fig. III, for a purpose to be later exthe armature is revolved in the opposite direction and screw 26 approaches the magnet core 22, the right hand end of the bridging member l5 extends under the member 3|, of insulating material, which is adjustably mounted upon the member 6, so as to render it impossible for the bridging member to be raised into contact with the member 6 until the armature is revolved and the opposite edge of the bridging member brought nearly into contact with the flexible member 28, as indicated in Fig. II.

An operation of my invention is substantially as follows, referring particularly to Fig, IV:

If the generator indicated at 3| be at rest, the switch will be open at contacts 6|51 and the lamps or translating devices, indicated at 32, may be supplied by the battery, shown at 33, through wires 34 and Under these conditions, and considering 3 as connected with the positive side of the battery, a very small current will flow from the battery 33 through wire 3:3, wire 36 having therein the fuse 31, to coil l3, and thence through wire 38 and wire to coil M, and thence through wire 5%, resistor ii, wire 12 and wire l? to the positive brush M of the generator 3!, and return to the battery 33 through the negative brush 45 of the generator and wire 35.

The coil 2 is of relatively very fine wire and has a great number of turns and, therefore, consumes very little current which may be con-- trolled by the value of resistance ti, but is capable of strongly energizing the core 2:2 upon which it is wound. As the member it has one end 28 (see Fig. 11) connected with the central portion 2! of the yoke of magnet frame 2l and its other end in close magnetic relation to the armature it at its mid-portion and separated therefrom only by a relatively thin washer of non-magnetic material 46, as shown in Figs. I and II, the flux set up by coil through core 22, yoke 2i, member it and the left-hand half of armature M will cause the armature to rotate until the screw 26 strikes the face of the magnet core and to be held in this position with the right-hand end of bridging member IE5 under the insulating block t l, as shown in Fig. II, preventing the switch from being accidentally closed. It", now, the generator be started, current will flow from wire :13, through wire coil iii, wire 68, and resistor iii, to wire and the generator. Coil iii is preferably of relatively quite fine wire and many turns, and may have its current adjusted by means of resistor 4t, and may be so wound as to increase the flux set up by coil 2-l when current flows from the battery through coil E l. As M has been considered as the positive brush of the generator, any voltage developed in the generator will oppose the current flowing from the battery 33 through the coil 2 and when the generator voltage equals that of the battery there will be no current in said coil. If the generator voltage slightly exceed the voltage of the battery, the current in coil 24 will flow in such direction as to oppose the flux of coil iii through core 22, and this will 5 cause core 23 to attract the right hand end of armature i more strongly than core 22 attracts the left-hand end; whereupon the armature will rotate toward core 23 and the right-hand end of bridging member l5 will come into contact-'5 with the flexible member As the member i5 is in communica ion with the wire :11, as by of the flexible ccnnector 50, current will now flow from the generator through wire t3, wire ll, flexible connector member l5, contac l528, wire coil 25, wire coil 53, wir and wire 3% to the battery and return to the generator through wire it.

lFhus, the generator will be connected to charge the battery with all the current passing through coil i3; and, as soon as this current is of any appreciable value, it '1 set up a very strong flux through magnet f1 aloe t-J--l l--i l and the armature M- and, by attracting the latter, raise the bridging member l5 into contact with contact members 6 and i; whereupon the generator will be connected through wire contact ":1, member ii, contact wire 52 and resistor with the wire thus providing a shunt of high carrying capacity around the coils l3 and 2%),

which coils may have their the value of resistor 53.

When the main contacts 'i-i5-'i are close as above pointed out, the air-gap between armature M and magnet frame 8-$-l9--ll is very short and, as t reluctance of t e magnetic current is then very low, great pressure is held upon the contacts with very little current flowing in coil l3, which may be only a relatively small fraction of the current carried by the main contacts, and, of course, this pressure will increase as the current supplied by the source increases. It, for any reason, the resistance of the main contacts should rise so as to cause undue heating, this will cause an undue proportion of the current to flow through coil l3, and if this fails to overcome the difficulty by increasing the contact pressure, the fuse 3'! will blow and protect the switch from damage by opening the main contacts and preventing closure until the trouble may be remedied and the fuse replaced.

With the generator supplying the circuit as above pointed out, if the generator voltage fall until very nearly that of the battery, the current in coil I3 will fall, and when this reaches a very low value the armature M will be released and the main contacts at i3-lii'l will be broken and the small current still supplied will flow through coils i3 and 2". Should the voltage of the generator rise and the current in coils l3 and incr-ase sufliciently, the main contacts will be closed again, as above pointed out. However, should the voltage of the generator continue to fall until very slightly below that of the battery, a slight back discharge will take place through coils l3 and 25, and this will oppose the flux set up by coil lb through ifi2 l23, and the flux through l5-2 l-EZ will predominate and attract the left hand end of armature M and break the connec tion between member [5 and member '28; and any back discharge then taking place will be through coil 24 tending to hold the switch open, as first above pointed out, in which position it will remain until the generator voltage slightly exceeds that of the battery, when the switch will again be closed, as above explained.

In Fig. V, a modification residing in the corn neotion of the coils is indicated, in that coil i3 has its upper end connected with wire #53 and wire 5! is connected by wire 5% with one end of the resistor 55, having its opposite end connected with one end of the field coil which has its opposite end in communication with the wire 35. The bridging member I5 is connected with the wire 3a through wire 52'. With this arrange the switch will operate as above outlined, save that whenever the generator is operative some current will flow from wire tl'irough coil coil 25, wire 54, resistor 55, coil 55, to wire This current, which is indicated as flowing through a field coil (which may be a more auxiliary coil) merely to show that it may perform a useful purpose and which may be regulated by the resistor 55 will, by flowing through coil tend to increase the flux set up by coil iii, through member 86, yoke 2|, core and the rig t-hand portion of armature M, at the time the rise in generator voltage is decreasing the current in the coil 24 and weakening its erlect on the flux set up by coil ii! in member l5, yoke 25, core 22 and the left-hand end of the armature Hi. There-- fore, the armature i l may be caused to rotate the bridging member 15 into contact with the flexible member 28 when the generator voltage is exactly equal to or even slightly below that of .urrent adjusted by the battery, as may be determined by adjustment of the resistor 55, in a manner that will be readily seen by those familiar with this art.

In the structure of Fig. VI, it will be noted that the member [6 has no winding thereupon, while the magnet legs 22 and 23 have coils 58 and 59 placed thereon, respectively. These coils are wound in such manner that both of the polar extremities of the cores are of the same polarity, while the fluxes through the cores traverse the air-gap to the armature l4, and return through the common limb IE to the yoke 2 I, or vice versa. These coils are shown in series and are, in effect, connected across the generator through a resistor 60, as indicated.

Core 22 is provided with a coil 6| which, in efifect, is connected across the contacts of the switch through the resistor 62, and is similar to coil 24 in Fig. IV, and has a similar function. Core 23 is provided with a coil 63 having one end connected with the flexible contact member 23, and its opposite end connected with one terminal of the coil l3, the opposite end of which is in communication with the wire 34. With this arrangement, if the generator be inoperative, current will flow from the battery through wire 34, resistor 62, coil 6|, wire 43, generator 3!, and wire 35, and hold the contact at I-28 open, as shown in Fig. II and as described with respect to the operation of Fig. IV.

If, now, the generator be started up, its voltage will oppose that of the battery and weaken the flux of coil 6 l while a small current will flow from the generator through wire 43, coil 58, coil 58, resistor 50, and wire 35, to the generator. The coils 58 and 59 are so wound that this current in coil 58 assists coil Bl as long as the current in BI is flowing from the battery to the generator; and, if 58 and 59 have the same number of turns, their effects upon armature I4, tending to revolve it about the pivot l1, will cancel each other as they are on opposite sides of the pivot. However, as soon as the generator voltage slightly exceeds that of the battery, the current in coil 6| will flow in such direction as to weaken the flux set up in core 22 by coil 58, and then coil 59 will have the stronger flux and will attract the righthand end of core l4 toward it and close the contact at l5-28; whereupon the generator will be connected with the battery, and the main current supplied thereby will flow through wire 43, member 1, pigtail 64, bridging member l5, contact member 28, coil 53, coil l3, wire 34, battery 33 and wire 35.

Coil 53 is so wound that this current tends to assist coil 59 in holding the contact I 528 closed, while this current flowing through coil l3 tends to raise the armature l4 and close the main contacts 6, I5, I, as described with respect to Fig. IV and, when the current reaches appreciable value, these main contacts will be closed and carry most of the current, as brought out in the operation of Fig. IV.

If, now, the generator voltage decrease until the current supplied by the generator is very small, coil l3 will release the armature l4 and the contacts at 6|5-1 will open, as described above with respect to the operation of Fig. IV.

If the generator voltage now fall until slightly less than that of the battery, a slight back discharge through coil 63 will oppose coil 59 and reduce the flux in core 23 below that in core 22, and coil 58 will thus cause the contact at I5-28 to be broken, and any further back discharge will then take place through coil BI and tend to hold the switch from being closed, as brought out with respect to the operation of Fig. IV.

It will here be noted that, by giving the coil 59 a few more turns than coil 58, the armature I4 may be caused to rotate the member 15 into contact with the member 28 and thus connect the generator and battery when the voltage of the generator is exactly equal to or slightly below that of the battery, if desired.

From the foregoing it will be seen that I have produced a switch which is capable of connecting a source of voltage with a circuit containing an opposing source and breaking the connection therebetween when the difference between the two voltages is very small, and which may have a high carrying capacity without the usual large and heavy parts employed in such switches.

It will also be noted that, while my switch has the advantages of a separate contactor with an independently operated delicate relay for operating the same, a single compact device having no delicate parts accomplishes this purpose.

It will also be plain that, owing to the shape of the magnets employed, excellent magnetic circuits may be obtained by using stacks of simple punchings of high grade electrical sheet.

I do not limit myself to any of the exact details of construction or modes of operation here given to illustrate embodiments of my invention, as wide departure may be made from the examples here given without departing from the spirit and scope of my invention, which is as set forth in the following claims.

I claim:

1. An automatic electric switch including electro-magnetic main circuit controlling means, auxiliary circuit controlling means for affecting the operation of the main controlling means, and a member movable in one plane operatively to afiect one of said means and in another plane operatively to affect the other means.

2. An automatic electric switch including main circuit controlling means, auxiliary circuit controlling means controlling the operation of the main controlling means, a member movable in one plane operatively to affect one of said means and in another plane operatively to affect the other means, and electro-magnetic means for moving said member.

3. An automatic electric switch including main circuit controlling means, auxiliary circuit controlling means, one position of which permits and another position of which prevents the operation of the main controlling means, a member movable in one plane to operate one of said means and in another plane to operate the other means, and electro-magnetic means for moving said member in both said planes.

4. An electric switch including main circuit controlling means, auxiliary circuit controlling means determining the operation of the main controlling means, a member movable in one direction operatively to affect one of said means and in another direction operatively to affect the other means, electromagnetic means for moving said member in one direction, and electromagnetic means controlled thereby for moving said member in another direction.

5. An electric switch for connecting two opposed sources of electrical potential difference, comprising contact mechanism and means for operating the same including a coil connecting the sources, a member affected by said coil to move in one direction to connect the sources, and means affected by the current flowing through said connection to move said member in another direction to cause another connection of said sources.

6. An electric switch for connecting two opposed sources of electrical potential difference, comprising contact mechanism and means for operating the same including a coil connecting the sources, a member aiTected by said coil to move in one direction to connect the sources, and means affected by the current flowing through said connection to move said member in another direction to cause another connection of said sources in shunt to the aforesaid connection.

'7. In apparatus of the class described, means for opening and closing an electric circuit, a voltage winding and a current winding for operating said means, a shunt circuit around said means and windings, and electro-magnetic means for opening and closing said shunt circuit in response to current changes in the first-named circuit.

8. In apparatus of the class described, means for opening and closing an electric circuit. a voltage winding and a current winding for operating said means, a shunt circuit around said means and windings, and electro-magnetic means for opening and closing said shunt circuit operatively affected by current in the first-named circuit.

9. In apparatus of the class described, means for opening and closing an electric circuit, a shunt circuit around said means, and means for opening and closing said shunt circuit operated by current in the first-named circuit alone, both said circuit opening and closing means in cluding a common element and being operated by motion of said element.

10. In a system of the type wherein a gencrator supplies a storage battery, an automatic switch comprehending means for connecting and disconnecting the generator and battery while their voltages are substantially equal throughout relatively wide variations in battery voltage, and means whereby current flowing through such connection establishes another connection between the generator and battery, said firstnamed means including a coil permanentl connecting the generator and battery and a coil carrying current through said named such connection.

11. In a system of the type wherein a generator supplies a storage battery, an automatic switch comprehending means for connecting and disconnecting the generator and battery while their voltages are substantially equal throughout rel-- atively wide variations in battery voltage, and means whereby current flowing through such connection establishes another connection between the generator and battery in shunt to the first-mentioned connection, said first-named means including a coil permanently connecting the generator and battery and a coil carrying current through said named such connection.

12. In a system of the type wherein a generator supplies a storage battery, an automatic switch comprehending means for connecting the generator and battery when their voltages become substantially equal, mee ns whereby current flowing through such connection establishes another connection. between the generator and battery in shunt to the first-mentioned connection, and means carrying current through the firstnamed connection only for causing both connections to be broken upon excess of current through the first-named connection.

13. Automatic means for connecting and dis connecting a supply circuit with a circuit to be supplied thereby, comprising a contact, means for making and breaking said contact comprising a movable magnetic member having magnet cores on each side of its center and separated from said member by an air gap, means tending to cause a magnetic flux through said magnetic member and both said cores, a winding upon one of said cores connected around said contact and a winding upon the other core in series with the contact, and means for making and breaking a shunt around said contact controlled by said contact.

14. Automatic means for conn-cting and disconnecting a supply circuit with a circuit to be supplied thereby, comprising a contact, means for making and breaking said contact comprising a movable magnetic member having magnet cores on each side of its center and separated from said member by an air gap, means tending to cause a magnetic flux through said magnetic member and both said cores, a winding upon one of said cores connected around said contact and a winding upon the other core in series with the contact, and means for making and breaking a shunt around said contact controlled by said contact comprising electromagnetic means responsive to current through said contact.

15. In a system of the character described, including, a generator and a storage battery; a switch for connecting said generator and said storage battery, having a coil responsive to generator voltage tending to close said switch, a coil for opposing the action of said first-mentioned coil, means for causing said first-mentioned coil to predominate over said seconcl-mentioned coil substantially when the generator voltage is substantially equal to the battery voltage, thereby to cause a closure of said switch, and means establishing and breaking a shunt around said switch controlled by current affected by said switch.

16. In an electrical system comprising a source of variable voltage and a circuit containing a source of voltage to be supplied thereby, means for connecting the first-named source with the circuit of the second-named source when the voltage of the first source is substantially equal to that of the second throughout relatively wide changes in voltage of the second source, and breaking said connection when the second-named source discharges back through the first, includ ing means for diverting current around said connection operatively affected only by current through said connection.

17. An electric switch including circuit controlling means, an electro-magnet for operating said means, means for controlling the operation of said first named means, another electro-magnet for controlling said last-named means, and a movable armature common to both said electro-magnets.

18. In apparatus of the class described, means for opening and closing an electric circuit, a shunt circuit around said means controlling the operation thereof, and means for opening and closing said shunt circuit including a coil in shunt to both said circuit opening and closing means.

JOHN L. CREVELING. 

